JP2012051062A - Mems device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MEMS device capable of electrically connecting pads of a device body and the conductive pattern of a mounting substrate via a surface side protective substrate and enhancing electric connection reliability while suppressing the application of unnecessary stress to the device body.SOLUTION: The MEMS device includes a mirror forming substrate (device body) 1 formed by using an SOI substrate (semiconductor substrate) 100 and provided with a plurality of pads 13 at one surface side, a MEMS chip 4 having a first cover substrate (surface side protective substrate) 2 joined to the one surface side of the mirror forming substrate 1 and the mounting substrate 5 on which the MEMS chip 4 is mounted. In the first cover substrate 2, a plurality of conduction parts 202 formed of silicon joined and electrically connected to respective pads 13 of the mirror forming substrate 1 are provided in the thickness dimension of the first cover substrate 2. The conduction parts 202 and conductor patterns 502 of the mounting substrate 5 are electrically connected via solder parts 6 formed so as to stride both of them.

Description

  The present invention relates to MEMS (micro electro mechanical systems) devices.

  Conventionally, for example, an optical scanner, an acceleration sensor, a gyro sensor, and the like are widely known as MEMS devices formed using a micromachining technique or the like.

  By the way, in this type of MEMS device, a MEMS chip is primarily mounted on a mounting board, and this mounting board is often used by being secondarily mounted on a wiring board such as a printed wiring board (for example, Patent Document 1). reference).

  Here, in Patent Document 1, as shown in FIG. 11C, a micromirror (device main body) 110 on which a movable mirror 124 is formed, and a base substrate (mounting substrate) 8 on which the micromirror 110 is mounted, An optical scanning device (optical scanner) including the above is disclosed. In this optical scanning device, the lower side of the micromirror 110 in FIG. 11C is sealed with the base substrate 8, and the upper side of the micromirror 110 is a transparent substrate (surface-side protective substrate) on which the light beam enters and exits. 7 is sealed. In the optical scanning device of FIG. 11C, the micromirror 110 and the transparent substrate 7 constitute a MEMS chip.

The above-described micromirror 110 is formed using an SOI (Silicon on Insulator) substrate 101 in which a first silicon substrate 101a and a second silicon substrate 101b are bonded together via an insulating layer (SiO ₂ layer) 101c. .

  As shown in FIGS. 11A and 11B, the micromirror 110 connects the fixed frame 111, the movable mirror 124 arranged inside the fixed frame 111, the fixed frame 111 and the movable mirror 124, and twists them. A pair of torsion spring portions 130 and 130 capable of deformation is provided. The micromirror 110 is of an electrostatic drive type, and movable electrodes (electric elements) 122 are formed on both sides of the movable mirror 124 in a direction orthogonal to the direction connecting the pair of torsion spring portions 130, 130. In addition, two fixed electrodes (electric elements) 112 facing each movable electrode 122 are formed. The micromirror 110 includes four pads 113 to which each movable electrode 122 and each fixed electrode 112 are connected individually.

  Here, in FIG. 11B, the pad 113 of the micromirror 110 and the lead terminal 806 of the base substrate 8 are electrically connected via the bonding wire 106. In contrast, in FIG. 11C, the metal portion 706 filled in the through hole 702 of the transparent substrate 7 and the lead terminal 806 of the base substrate 8 are electrically connected via the bonding wire 106.

  In the optical scanning device shown in FIG. 11C, a concave portion 810 serving as a swinging space for the movable mirror 124 is formed at the center of the surface of the base substrate 8 on the micromirror 110 side. Since the space surrounded by the fixed frame 111 and the base substrate 8 is a vacuum, the swing angle of the movable mirror 124 of the micromirror 110 can be increased.

JP 2005-257944 A

  By the way, in the optical scanning device shown in FIG. 11C, a through-hole 702 is formed in a part of the transparent substrate 7 bonded to the micromirror 110, and the movable electrode 122 is filled with metal later. Each fixed electrode 112 can be electrically connected to the lead terminal 806 of the base substrate 8 through the metal portion 706 and the bonding wire 106.

  However, in the optical scanning device shown in FIG. 11C, since the bonding wire 106 protrudes from the surface of the transparent substrate 7, the bonding wire 106 is damaged by contact with an external object during handling or the like. There was a fear of doing. In order to protect the bonding wire 106, it may be possible to provide a protective portion made of a resin covering the bonding wire 106, but a large amount of resin is required for the protective portion, and the stress applied to the micromirror 110 due to the protective portion. There is a risk that the characteristic will change due to the increase in the thickness of the resin, and the resin will flow over the light incident part and the light emission part in the transparent substrate 7 at the time of manufacture, thereby forming irregularities due to the resin and changing the optical characteristic.

  The present invention has been made in view of the above-described reasons, and the object thereof is to electrically connect the pad of the device body and the conductor pattern of the mounting substrate through the surface-side protective substrate, and to provide unnecessary stress on the device body. It is an object of the present invention to provide a MEMS device capable of improving electrical connection reliability while suppressing the occurrence of such a problem.

  A MEMS device according to the present invention includes a device main body formed using a semiconductor substrate and provided with a plurality of pads on one surface side, a MEMS chip having a surface-side protective substrate bonded to the one surface side of the device main body, A mounting substrate on which a MEMS chip is mounted, and the surface-side protection substrate includes a plurality of conductive portions made of silicon bonded to and electrically connected to the pads of the device body, and the surface-side protection Each conductive pattern provided within the thickness dimension of the substrate and associated with each conductive portion in the mounting substrate and the mounting substrate is formed across the conductive portion and the conductive pattern. It is electrically connected through a solder part.

  In this MEMS device, the conductive portion extends to the side surface of the front surface side protective substrate within the thickness dimension of the front surface side protective substrate on the side opposite to the device body side of the front surface side protective substrate. Is preferred.

  In this MEMS device, the MEMS chip includes a back surface side protective substrate bonded to the other surface side of the device body, and is surrounded by a peripheral portion of the device body, the surface side protective substrate, and the back surface side protective substrate. The space is preferably an airtight space.

  In this MEMS device, it is preferable that the MEMS chip has a vacuum atmosphere in the airtight space, and a getter is disposed at a portion facing the airtight space on one of the front surface side protective substrate and the back surface side protective substrate. .

  In this MEMS device, it is preferable that the mounting substrate has a recess that is recessed from a plane including the conductor pattern, and the MEMS chip is mounted on an inner bottom surface of the recess.

  In this MEMS device, the device main body includes an outer frame portion to which a peripheral portion of the surface-side protection substrate is bonded on the one surface side, and a pair of first twisted spring portions disposed inside the outer frame portion. And a pair of second twists arranged in parallel in a direction orthogonal to the juxtaposition direction of the first twisted springs located inside the movable frame part and the movable frame part supported by the outer frame part A mirror part supported by the movable frame part via a spring part, a first fixed electrode provided on the movable frame part side in the outer frame part, and provided on the outer frame part side in the movable frame part The first movable electrode, the second fixed electrode provided on the mirror part side in the movable frame part, and the movable frame part side provided on the mirror part. Each of the pads electrically connected to each of the first movable electrode, the first fixed electrode, the second movable electrode, and the second fixed electrode. Is preferably arranged in the outer frame portion.

  In the MEMS device of the present invention, the pad of the device body and the conductor pattern of the mounting substrate can be electrically connected through the surface side protective substrate, and the electrical connection is performed while suppressing unnecessary stress on the device body. Reliability can be increased.

The MEMS device (optical scanner) of Embodiment 1 is shown, (a) is a schematic perspective view, (b) is a principal part schematic sectional drawing. It is a schematic exploded perspective view of a MEMS device same as the above. The MEMS chip | tip in a MEMS device same as the above is shown, (a) is a schematic plan view, (b) is an AA schematic sectional view of (a), (c) is an AB schematic sectional view of (a). It is main process sectional drawing for demonstrating the manufacturing method of the MEMS chip | tip in a MEMS device same as the above. It is main process sectional drawing for demonstrating the manufacturing method of the MEMS chip | tip in a MEMS device same as the above. FIG. 6 is a schematic exploded perspective view of a MEMS device (optical scanner) according to a second embodiment. It is a schematic perspective view of a MEMS device same as the above. It is a schematic perspective view of the MEMS chip in a MEMS device same as the above. It is main process sectional drawing for demonstrating the manufacturing method of the MEMS chip | tip in a MEMS device same as the above. It is main process sectional drawing for demonstrating the manufacturing method of the MEMS chip | tip in a MEMS device same as the above. A conventional example is shown, (a) is a schematic plan view of a micromirror, (b) is a schematic cross-sectional view corresponding to the AA cross section of (a) and the micromirror is mounted on a base substrate, (c) is It is a schematic sectional drawing of the optical scanning apparatus corresponding to the AA cross section of (a).

(Embodiment 1)
In this embodiment, an optical scanner is illustrated as an example of a MEMS device.

  Hereinafter, the optical scanner of the present embodiment will be described with reference to FIGS.

  The optical scanner of this embodiment includes a MEMS chip 4 and a mounting substrate 5 on which the MEMS chip 4 is mounted.

  The MEMS chip 4 includes a mirror forming substrate 1 formed using an SOI substrate 100 and having a mirror surface (optical element) 21 provided on a movable portion 20. Here, the mirror forming substrate 1 includes a plurality of pads 13 on one surface side where the mirror surface 21 is provided. The MEMS chip 4 also includes a first cover substrate 2 bonded to the one surface side of the mirror forming substrate 1. The MEMS chip 4 includes a second cover substrate 3 bonded to the other surface side of the mirror forming substrate 1. In the present embodiment, the SOI substrate 100 constitutes a semiconductor substrate. In the present embodiment, the mirror forming substrate 1 constitutes the device body, the first cover substrate 2 constitutes the front surface side protective substrate, and the second cover substrate 3 constitutes the back surface side protective substrate. ing.

  The mirror forming substrate 1 includes a frame-shaped (here, rectangular frame-shaped) outer frame portion 10, the above-described movable portion 20 disposed inside the outer frame portion 10, and a movable portion 20 inside the outer frame portion 10. And a pair of torsion spring parts (mechanical elements) 30 and 30 that are connected to the outer frame part 10 and the movable part 20. Each of the torsion springs 30 and 30 can be torsionally deformed.

  The outer frame portion 10 has an outer peripheral shape and an inner peripheral shape that are each formed in a rectangular shape. Here, in the MEMS chip 4, the outer peripheral shape of each of the mirror forming substrate 1 and each of the cover substrates 2 and 3 is rectangular, and the outer dimensions of each of the cover substrates 2 and 3 are matched with the outer dimensions of the mirror forming substrate 1. It is.

  In the mirror forming substrate 1, the planar view shape of the movable portion 20 is rectangular, and the planar view shape of the mirror surface 21 is also rectangular.

The mirror forming substrate 1 is formed by processing the above-described SOI substrate 100 by a bulk micromachining technique or the like. In the SOI substrate 100, an insulating layer (SiO ₂ layer) 100c is interposed between a conductive first silicon layer 100a and a second silicon layer (silicon substrate) 100b. In the SOI substrate 100, the thickness of the first silicon layer 100a is set to 400 μm, and the thickness of the second silicon layer 100b is set to 400 μm. However, these numerical values are examples, and are not particularly limited. Absent. The surface of the first silicon layer 100a, which is one surface of the SOI substrate 100, is a (100) plane. Moreover, although the external size of the mirror formation board | substrate 1 is about several mm □, it does not specifically limit.

  The outer frame portion 10 of the mirror forming substrate 1 is formed using the first silicon layer 100a, the insulating layer 100c, and the second silicon layer 100b of the SOI substrate 100, respectively. In the mirror forming substrate 1, a portion of the outer frame portion 10 formed by the first silicon layer 100 a is joined to the outer peripheral portion of the first cover substrate 2 over the entire periphery. Of these, the portion formed by the second silicon layer 100 b is bonded to the outer periphery of the second cover substrate 3 over the entire periphery. Further, the mirror forming substrate 1 has two pads 13 to be described later formed on the outer frame portion 10 on the one surface side. Each pad 13 has a circular shape in plan view, and is composed of a first metal film (for example, an Al—Si film). In this embodiment, the film thickness of each pad 13 is set to 500 nm, but this numerical value is an example and is not particularly limited. Here, each pad 13 is provided for power supply from the outside, and the material of each pad 13 may be any material that can make ohmic contact with the first silicon layer 100a. Not only Si but Au, Al, etc. may be adopted.

  Further, the movable portion 20 and the torsion spring portions 30, 30 of the mirror forming substrate 1 are formed using the first silicon layer 100 a of the SOI substrate 100 and are sufficiently thinner than the outer frame portion 10. Yes. The mirror surface 21 provided in the movable part 20 reflects light from a light source (laser light source or the like), and is formed on a part of the movable part 20 formed by the first silicon layer 100a. The reflection film 21a is composed of two metal films (for example, an Al—Si film). In the present embodiment, the thickness of the reflective film 21a is set to 500 nm, but this numerical value is an example and is not particularly limited.

  In the following, as shown in the lower left of each of FIGS. 3A, 3B, and 3C, the direction orthogonal to the parallel direction of the pair of torsion spring portions 30, 30 in plan view is the x-axis direction, and the pair of The parallel arrangement direction of the torsion springs 30 and 30 will be described as the y-axis direction, and the direction orthogonal to the x-axis direction and the y-axis direction will be described as the z-axis direction.

  In the mirror forming substrate 1, a pair of torsion spring portions 30, 30 are arranged in parallel in the y-axis direction, and the movable portion 20 can be displaced around the pair of torsion spring portions 30, 30 with respect to the outer frame portion 10. (It can be rotated around the axis in the y-axis direction). That is, the pair of torsion spring portions 30, 30 connects the outer frame portion 10 and the movable portion 20 so that the movable portion 20 can swing with respect to the outer frame portion 10. In other words, the movable portion 20 disposed inside the outer frame portion 10 is connected to the outer frame portion 10 via two torsion spring portions 30 and 30 that are continuously and integrally extended in two opposite directions from the movable portion 20. It is swingably supported. Here, the pair of torsion spring portions 30 and 30 are formed such that a straight line connecting the center lines along the y-axis direction passes through the center of gravity of the movable portion 20 in plan view. Each of the torsion spring portions 30 and 30 has a thickness dimension (dimension in the z-axis direction) set to 30 μm and a width dimension (dimension in the x-axis direction) set to 5 μm, but these numerical values are examples. There is no particular limitation. Moreover, the planar view shape of the movable part 20 and the mirror surface 21 is not limited to a rectangular shape, and may be a circular shape, for example. Further, the inner peripheral shape of the outer frame portion 10 is not limited to a rectangular shape, and may be a circular shape, for example.

  The mirror forming substrate 1 described above has both sides in a direction (that is, the x-axis direction) orthogonal to the direction connecting the pair of torsion spring portions 30 and 30 (the direction in which the pair of torsion spring portions 30 and 30 are juxtaposed) in the movable portion 20. A comb-shaped movable electrode 22 is provided. Further, the mirror forming substrate 1 includes a comb-shaped fixed electrode 12 having a plurality of fixed comb teeth 12b formed on the outer frame portion 10 and facing the plurality of movable comb teeth 22b of the movable electrode 22. Here, the movable electrode 22 and the fixed electrode 12 constitute an electrostatic drive type driving means for driving the movable portion 20 by electrostatic force. In the present embodiment, the driving means drives the movable part 20 by electrostatic force. However, the driving means is not limited to an electrostatic drive type, and may be an electromagnetic drive type that drives the movable part 20 by an electromagnetic force, for example. Alternatively, a piezoelectric drive type in which the movable portion 20 is driven by a piezoelectric element may be used.

  The above-described fixed electrode 12 has a comb shape in plan view, and a part of the portion formed by the first silicon layer 100a in the frame piece portion along the y-axis direction in the outer frame portion 10 is a comb bone. Part 12a is configured. The fixed electrode 12 has a pair of torsion spring portions 30 having a large number of fixed comb teeth 12b on the surface facing the movable portion 20 of the comb bone portion 12a (the inner surface along the y-axis direction of the outer frame portion 10). , 30 are arranged in a line along the juxtaposed direction. Here, each fixed comb tooth piece 12b is constituted by a part of the first silicon layer 100a.

  On the other hand, the movable electrode 22 is a part of the first silicon layer 100a on the side surface (side surface along the y-axis direction of the movable portion 20) of the comb portion 22a on the side of the comb portion 12a of the fixed electrode 12 in the movable portion 20. A large number of movable comb teeth 22b that are constituted by the portions and respectively face the fixed comb teeth 12b are arranged in the parallel direction. Here, each movable comb-tooth piece 22b is constituted by a part of the first silicon layer 100a.

  In the comb-shaped fixed electrode 12 and the comb-shaped movable electrode 22, the comb bone portions 12 a and 22 a face each other, and the fixed comb teeth 12 b of the fixed electrode 12 are arranged in the comb grooves of the movable electrode 22. The fixed comb teeth 12b and the movable comb teeth 22b are separated from each other in the y-axis direction. Therefore, in the driving means, an electrostatic force acting in a direction attracting each other is generated between the fixed electrode 12 and the movable electrode 22 by applying a voltage between the fixed electrode 12 and the movable electrode 22. In addition, what is necessary is just to set the clearance gap between the fixed comb-tooth piece 12b and the movable comb-tooth piece 22b in a y-axis direction suitably in the range of about 2 micrometers-5 micrometers, for example.

  In the portion formed by the first silicon layer 100a in the outer frame portion 10 of the mirror forming substrate 1, one pad 13 (left pad 13a in FIG. 2) is electrically connected to each movable electrode 22. A plurality (here, the other pad 13 (the right pad 13b in FIG. 2) is electrically connected to each fixed electrode 12, and each fixed electrode 12 and each movable electrode 22 are electrically insulated. Then, three slits 10a are formed to a depth reaching the insulating layer 100c. Thereby, the portion formed by the first silicon layer 100a in the outer frame portion 10 is the same as the first conductive structure 11a having the same potential as each movable electrode 22 of the movable portion 20 and each fixed electrode 12. It is divided into a second conductive structure 11b that becomes a potential.

  The first conductive structure 11a has an island shape (here, in plan view) in which two anchor portions 11aa and 11ab connected to the respective torsion spring portions 30 and 30 are integrally connected and one pad 13a is formed. (Rectangular shape) conductive portion 11ac, and L-shaped conductive portion 11ad in plan view that connects one anchor portion 11aa and island portion 11ac. The second conductive structure 11b is formed of the remaining portion of the first silicon layer 100a other than the first conductive structure 11a, and the other pad 13b is formed.

  Here, in the mirror forming substrate 1, each slit 10 a formed in the first silicon layer 100 a is a trench, and the shape of each slit 10 a in plan view is a shape that is not opened to the outer surface side of the outer frame portion 10. Therefore, in the MEMS chip 4 according to the present embodiment, the bonding property between the outer frame portion 10 and the first cover substrate 2 is reduced while adopting a structure in which the outer frame portion 10 is formed with a plurality of slits 10a. Can be prevented, and the airtightness of the space surrounded by the outer frame portion 10 and the cover substrates 2 and 3 can be ensured.

  The first cover substrate 2 includes a flat cover body 200 made of glass, and a plurality of first cover substrates 2 that are provided so as to penetrate in the thickness direction of the cover body 200 and are joined and electrically connected to the respective pads 13. The conductive portion 202 is provided. In short, the first cover substrate 2 is provided with a plurality of conductive portions 202 made of silicon that are bonded to and electrically connected to the pads 13 of the mirror forming substrate 1 within the thickness dimension. In addition, although the thickness of the 1st cover board | substrate 2 is set to 300 micrometers, this numerical value is an example and it does not specifically limit it.

  Here, the MEMS chip 4 has a first portion in each of the movable portion 20 and the pair of twisted spring portions 30 and 30 in order to ensure a displacement space of the movable portion 20 in the mirror forming substrate 1 toward the first cover substrate 2. The thickness of the silicon layer 100a is reduced. In short, the thickness of the first silicon layer 100a is made thinner inside the outer frame portion 10.

  In the MEMS chip 4 in the present embodiment, the shape of each pad 13 in plan view is a circular shape having a diameter of 0.5 mm, and the diameter of the end surface of each conductor portion 202 on the mirror forming substrate 1 side is smaller than 0.5 mm. Although set, these diameters are not particularly limited. Further, although the pad 13 is made large, the diameter of each pad 13, 13 is not particularly limited, and the shape of the pad 13 does not necessarily need to be a circular shape. Good.

  The conductive portion 202 extends to the side surface of the first cover substrate 2 within the thickness dimension of the first cover substrate 2 on the opposite side of the first cover substrate 2 from the mirror forming substrate 1 side. The unit 203 is provided.

  The second cover substrate 3 is formed by processing a glass substrate 300 made of Pyrex (registered trademark) glass or the like. In addition, although the thickness of the glass substrate 300 is set in the range of about 0.5 mm to 1.5 mm, this numerical value is an example and is not particularly limited.

  The second cover substrate 3 has a recess 301 formed on one surface of the glass substrate 300 on the mirror forming substrate 1 side. In the second cover substrate 3, the concave portion 301 constitutes a displacement space forming concave portion for securing the displacement space of the movable portion 20. However, even if both surfaces in the thickness direction of the second cover substrate 3 are planar, if the second cover substrate 3 does not hinder the displacement of the movable portion 20 in the z-axis direction, the recess 301 is not necessarily formed. do not have to.

  When the recess 301 is formed on the one surface of the glass substrate 300, for example, it may be formed by a sandblast method or the like. Further, the second cover substrate 3 may be formed by joining two glass plates, and is recessed in a glass plate (hereinafter referred to as a first glass plate) disposed on the side close to the mirror forming substrate 1. A glass plate (hereinafter referred to as a second glass plate) disposed on the side far from the mirror forming substrate 1 while forming an opening portion penetrating in the thickness direction in a portion corresponding to 301 may be formed into a flat plate shape. Since the second cover substrate 3 does not need to transmit light, the second cover substrate 3 is not limited to the glass substrate 300 but can be easily bonded to the mirror forming substrate 1 and Si, which is a material of the semiconductor substrate (SOI substrate 100). For example, a silicon substrate may be used, and the concave portion 301 in this case may be formed using a photolithography technique and an etching technique. That's fine.

  The glass material of the glass substrate 300 is preferably borosilicate glass that can be easily bonded to the mirror forming substrate 1 and has a small difference in linear expansion coefficient from Si that is a material of the semiconductor substrate (SOI substrate 100). For example, Corning Pyrex (registered trademark) or Schott Tempax (registered trademark) may be used, but not only borosilicate glass but also soda lime glass, alkali-free glass, quartz glass, etc. May be. In the present embodiment, the depth of the recess 301 is set in a range of 300 μm to 800 μm. However, these numerical values are merely examples, and may be appropriately set according to the amount of displacement of the movable portion 20 in the z-axis direction. What is necessary is just to be the depth which does not prevent the rotational movement of the movable part 20 (that is, what is necessary), and it does not specifically limit.

  Further, in the above-described MEMS chip 4, the airtight space surrounded by the outer frame portion 10 of the mirror forming substrate 1, the first cover substrate 2, and the second cover substrate 3 is evacuated to reduce power consumption. It is possible to increase the mechanical deflection angle of the movable portion 20 while being planned. Therefore, in the MEMS chip 4 described above, the airtight space is evacuated. Further, in the MEMS chip 4 described above, an appropriate portion inside the portion that is bonded to the outer frame portion 10 on the surface of the second cover substrate 3 facing the mirror forming substrate 1 (here, the inner bottom surface of the recess 301). A film-like getter 9 is arranged on the surface. The getter 9 is preferably a non-evaporable getter, and may be formed of, for example, an alloy containing Zr as a main component or an alloy containing Ti as a main component.

  In the MEMS chip 4 described above, each conductive part 202 and each conductive pattern 502 associated with each conductive part 202 in the mounting substrate 5 are formed so as to straddle the conductive part 202 and the conductive pattern 502. It is electrically connected via the part 6. Here, a metal layer made of a metal material (for example, Au, Al, etc.) that has good wettability with the solder that is the material of the solder portion 6 is formed at the joint portion of the conductive portion 202 with the solder portion 6. It is preferable. Further, in this embodiment, since the conductive portion 202 includes the above-described extending portion 203, the conductive portion 202 and the conductor pattern 502 are formed so that the solder portion 6 is formed along the extending direction of the extending portion 203. It is preferable to set the relative positional relationship of. Alternatively, it is preferable to set the extending direction of the extending portion 203 based on the positional relationship between the conductive portion 202 and the conductive pattern 502. The extending portion 203 is not necessarily provided. In this case, the conductive portion 202 penetrating in the thickness direction of the cover body 200 and the conductor pattern 502 of the mounting substrate 5 are electrically connected via the solder portion 6. That's fine.

  Next, the operation of the MEMS chip 4 will be briefly described.

  In the MEMS chip 4 in this embodiment, the movable electrode 22 is fixed by applying a pulse voltage for driving the movable portion 20 between the movable electrode 22 and the fixed electrode 12 facing each other through the pair of pads 13 and 13. An electrostatic force is generated between the electrodes 12, and the movable part 20 rotates about the axis in the y-axis direction. Therefore, in the MEMS chip 4 in the present embodiment, by applying a pulse voltage having a predetermined driving frequency between the movable electrode 22 and the fixed electrode 12, an electrostatic force can be periodically generated, and the movable part 20 is It can be swung.

  Here, the above-mentioned movable part 20 is not in a horizontal posture (attitude parallel to the xy plane) and is tilted slightly though it is stationary due to internal stress. For example, the movable electrode 22 is fixed. When a pulse voltage is applied between the electrodes 12, a driving force in a direction substantially perpendicular to the movable portion 20 (z-axis direction) is applied even from a stationary state, so that the movable portion 20 has a pair of torsion spring portions 30, The pair of torsion springs 30 and 30 are rotated while twisting about 30 as a rotation axis. Then, when the driving force between the movable electrode 22 and the fixed electrode 12 is released when the movable comb tooth piece 22b and the fixed comb tooth piece 12b are in a posture that completely overlaps, the movable portion 20 has an inertial force. Thus, the pair of torsion springs 30 and 30 continue to rotate while twisting. Then, when the inertial force in the rotational direction of the movable portion 20 and the restoring force of the pair of torsion spring portions 30 and 30 become equal, the rotation of the movable portion 20 in the rotational direction stops. At this time, when an electrostatic force is generated again by applying a pulse voltage between the movable electrode 22 and the fixed electrode 12, the movable portion 20 is caused by the restoring force of the pair of torsion spring portions 30, 30 and the movable electrode 22 and the fixed electrode 12. By the driving force of the configured driving means, the rotation in the opposite direction is started. The movable portion 20 repeats the rotation by the driving force of the driving means and the restoring force of the pair of torsion spring portions 30 and 30, and swings about the pair of torsion spring portions 30 and 30 as the rotation shaft.

  In the MEMS chip 4 in the present embodiment, the movable part 20 is applied by applying a pulse voltage having a frequency approximately twice the resonance frequency of the vibration system constituted by the movable part 20 and the pair of torsion spring parts 30 and 30. Driven with a resonance phenomenon, the mechanical deflection angle (tilt with respect to a horizontal plane parallel to the xy plane) increases. The application form and frequency of the voltage (drive voltage) between the movable electrode 22 and the fixed electrode 12 are not particularly limited. For example, the voltage applied between the movable electrode 22 and the fixed electrode 12 may be a sine wave voltage. Good.

  Hereinafter, a method for manufacturing the MEMS chip 4 in the MEMS device according to the present embodiment will be described with reference to FIG. 4. FIGS. 4A to 4D are schematic views of a portion corresponding to a cross section A-B in FIG. A cross section is shown.

  First, in the first silicon layer 100a of the SOI substrate 100 that is a semiconductor substrate, a region inside the region corresponding to the outer frame portion 10 is thinned by using a photolithography technique and an etching technique. Thereafter, a metal film forming step of forming a metal film (for example, an Al film) having a predetermined film thickness (for example, 500 nm) on the one surface side of the SOI substrate 100 by a sputtering method, a vapor deposition method, or the like is performed. Then, by performing a metal film patterning step of forming each pad 13 and the reflective film 21a by patterning the metal film using an etching technique, the structure shown in FIG. 4A is obtained. In this embodiment, since the material and film thickness of each pad 13 and the reflective film 21a are set to be the same, each pad 13 and the reflective film 21a are formed simultaneously. When the material and film thickness of the film 21a are different, the pad forming process for forming each pad 13 and the reflecting film forming process for forming the reflecting film 21a may be provided separately. Either may be the first in order with the formation step.

  After forming each of the pads 13 and the reflective film 21a, on the one surface side of the SOI substrate 100, the movable portion 20, the pair of torsion spring portions 30 and 30, the outer frame portion 10, of the first silicon layer 100a, A first resist layer 107 patterned so as to cover the portions corresponding to the fixed electrodes 12 and the movable electrodes 22 is formed. Subsequently, by using the first resist layer 107 as a mask, a first silicon layer patterning step (surface side patterning step) for patterning the first silicon layer 100a is performed to obtain the structure shown in FIG. . In the first silicon layer patterning step, a portion of the first silicon layer 100a that is not covered with the first resist layer 107 is etched to a depth that reaches the insulating layer 100c (first predetermined depth). . The etching of the first silicon layer 100a in the first silicon layer patterning step may be performed by a dry etching apparatus capable of highly anisotropic etching such as an inductively coupled plasma (ICP) type etching apparatus. In the first silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

  After the first silicon layer patterning step, the first resist layer 107 on the one surface side of the SOI substrate 100 is removed. Thereafter, a second resist layer 108 is formed on the entire surface of the SOI substrate 100 on the one surface side, and then, on the other surface side of the SOI substrate 100, corresponding to the outer frame portion 10 of the second silicon layer 100b. A third resist layer 109 patterned so as to expose portions other than the portion is formed. Then, using the third resist layer 109 as a mask, a second silicon layer patterning process for patterning the second silicon layer 100b is performed, thereby obtaining the structure shown in FIG. In the second silicon layer patterning step, the second silicon layer 100b is etched to a depth that reaches the insulating layer 100c (second predetermined depth). In short, the second silicon layer patterning step constitutes a back side patterning step of etching the SOI substrate 100, which is a semiconductor substrate, from the other surface to a second predetermined depth. Etching of the second silicon layer 100b in the second silicon layer patterning step may be performed by a dry etching apparatus that has high anisotropy and enables vertical deepening, such as an inductively coupled plasma (ICP) etching apparatus. In the second silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

  After the above-described second silicon layer patterning step, a portion between the outer frame portion 10 and the movable portion 20 and a portion between the movable electrode 22 and the fixed electrode 12 facing each other in the insulating layer 100c of the SOI substrate 100 are formed. Then, the mirror forming substrate 1 is formed by performing an insulating layer patterning step of etching from the other surface side of the SOI substrate 100. Subsequently, the second resist layer 108 and the third resist layer 109 are removed. Thereafter, the MEMS chip 4 having the structure shown in FIG. 4D is obtained by performing a bonding step of bonding the mirror forming substrate 1 to the first cover substrate 2 and the third cover substrate 3 by anodic bonding or the like. .

  In the above-described bonding process, from the viewpoint of protecting the mirror surface 21 of the mirror forming substrate 1, after performing the first bonding process of bonding the first cover substrate 2 and the mirror forming substrate 1, It is preferable to perform a second joining process for joining the second cover substrate 3. Here, in the first bonding process, the laminated body in which the first cover substrate 2 and the mirror forming substrate 1 are stacked is subjected to a predetermined bonding temperature (for example, 300 Pa) in a vacuum with a predetermined degree of vacuum (for example, 10 Pa or less). In the state heated to about 400 to about 400 ° C., a predetermined voltage (for example, about 400V to 800V) is set between the first silicon layer 100a and the first cover substrate 2 with the first cover substrate 2 side being a low potential side. ), And this state may be maintained for a predetermined joining time (for example, about 20 to 60 minutes). In the second bonding process, anodic bonding between the second silicon layer 100b and the second cover substrate 3 is performed in accordance with the first bonding process described above. The bonding method for bonding the mirror forming substrate 1 to the first cover substrate 2 and the second cover substrate 3 is not limited to anodic bonding, and may be, for example, a surface activated bonding method (for example, room temperature bonding method). . In addition, after the first silicon layer patterning step, the SOI substrate 100 and the first cover substrate 2 are bonded together, and then the second silicon layer patterning step and the insulating layer patterning step are performed, so that the mirror forming substrate 1 is formed. Then, the mirror forming substrate 1 and the second cover substrate 3 may be bonded.

  In the manufacturing method of the MEMS chip 4 described above, the MEMS chip 4 is obtained by performing all the processes until the bonding process is completed on the mirror forming substrate 1, the first cover substrate 2, and the second cover substrate 3 at the wafer level. A wafer level package structure including a plurality of wafers is formed, and a dividing step of dividing the wafer level package structure into individual MEMS chips 4 is performed. In short, in the method of manufacturing the MEMS chip 4 in the present embodiment, a first wafer having a plurality of mirror forming substrates 1 and a second wafer having a plurality of first cover substrates 2 (here, a wafer-like structure). And a third wafer on which a plurality of second cover substrates 3 are formed are joined together to form a wafer level package structure, and then the wafer level package structure is divided into the outer size of the mirror forming substrate 1. As a result, the planar size of the first cover substrate 2 and the second cover substrate 3 can be adjusted to the outer size of the mirror forming substrate 1, so that the mass productivity of the small MEMS chip 4 can be improved. .

  In forming the first cover substrate 2, the one surface side of the silicon substrate 250 is first processed by processing one surface side of the silicon substrate 250, which is a conductive substrate, as shown in FIG. The convex part 202a used as the base of the electroconductive part 202 (here, when the electroconductive part 202 is provided with the extending part 203) is formed. Thereafter, as shown in FIG. 5B, the surface of the silicon substrate 250 is flattened by applying glass to the surface of the silicon substrate 250, whereby the glass serving as the base of the cover body 200 is formed on the one surface side of the silicon substrate 250. The structure 200a is formed. Subsequently, as shown in FIG. 5C, from the surface side of the glass structure 200a (lower surface side in FIG. 5B) and the other surface side of the silicon substrate 250 (upper surface side in FIG. 5B). By polishing, both end surfaces of the conductive portion 202 are exposed.

  Also, the mounting substrate 5 described above has a plurality of conductor patterns (electrodes) 502 formed on one surface side, in which each pad 13 of the MEMS chip 4 is electrically connected via the conductive portion 202 and the solder portion 6. Yes.

  Further, the mounting substrate 5 straddles the side surface (the inner surface of the notch formed on the side surface) and the back surface so that it can be surface-mounted when performing secondary mounting on a wiring substrate (circuit board) such as a printed wiring board. An external connection electrode 504 made of a continuous conductor pattern (terminal pattern) is formed. Therefore, in the MEMS device of this embodiment, when the mounting substrate 5 is secondarily mounted on the wiring substrate, a solder fillet can be formed, and the mounting strength can be improved. The mounting substrate 5 is also provided with a conductor pattern 503 for wiring that electrically connects each conductor pattern 502 and the external connection electrode 504. However, if the mounting substrate 5 is arranged such that the conductor pattern 502 and the external connection electrode 504 are continuously formed, the conductor pattern 503 for wiring need not be provided.

  By the way, as described above, the first cover substrate 2 of the MEMS chip 4 is formed with the conductive portions 202 that are electrically connected to the respective pads 13 of the mirror forming substrate 1. Here, each conductor pattern 502 of the mounting substrate 5 has a short distance from the corresponding pad 13 (the pad 13 electrically connected via the conductive portion 202 and the solder portion 6) of the mirror forming substrate 1 in the MEMS chip 4. The extending portion 203 is formed so as to run along the direction in which the corresponding pads 13 and the conductor pattern 502 are aligned one-on-one.

  Further, the mounting substrate 5 has a recess 501 that is recessed from the plane including the conductor pattern 502 at the center, and the MEMS chip 4 is mounted on the inner bottom surface of the recess 501. Therefore, in the MEMS device of this embodiment, the height difference between the pad 13 and the conductor pattern 502 in the direction along the thickness direction of the mirror forming substrate 1 is set by appropriately setting the depth dimension of the recess 501 of the mounting substrate 5. The connection reliability by the solder part 6 can be improved. Here, the depth dimension of the recess 501 of the mounting substrate 5 may be appropriately set according to the height from the back surface of the MEMS chip 4 to the surface of the pad 13. In other words, the height difference between the pad 13 and the conductor pattern 502 in the direction along the thickness direction of the mirror forming substrate 1 can be adjusted by appropriately setting the depth dimension of the recess 501 of the mounting substrate 5. In order to form the solder portion 6 like a so-called solder bridge, it is preferable that the height difference is substantially zero. The MEMS chip 4 is bonded to the mounting substrate 5 using a die bond material (die bonded). As the die bond material, for example, a resin-based die bond material (for example, a silicone resin or an epoxy resin) may be employed. However, the height dimension accuracy from the inner bottom surface of the recess 501 of the mounting substrate 5 to the surface of the pad 13 is not limited. For example, a resin mixed with a large number of spherical spacers may be used. The mounting substrate 5 is formed of a ceramic substrate, but is not limited to a ceramic substrate.

  In manufacturing the MEMS device of the present embodiment, a chip mounting process is performed in which the MEMS chip 4 manufactured by the above-described manufacturing method of the MEMS chip 4 is bonded to the mounting substrate 5 to be mounted on the mounting substrate 5. What is necessary is just to perform the electrical connection process which electrically connects the electroconductive part 202 of the 1st cover substrate 2 in the chip | tip 4 and the conductor pattern 502 of the mounting board | substrate 5 via the solder part 6. FIG.

  According to the MEMS device (optical scanner) of the present embodiment described above, a plurality of conductive layers made of silicon bonded to and electrically connected to the respective pads 13 of the mirror forming substrate 1 to the first cover substrate 2. The portion 202 is provided within the thickness dimension of the second cover substrate 2, and each conductive portion 202 and each conductor pattern 502 associated with each conductive portion 202 in the mounting substrate 5 are connected to the conductive portion 202 and the conductor. It is electrically connected via the solder part 6 formed across the pattern 502. Thus, in the MEMS device of the present embodiment, the pad 13 of the mirror forming substrate 1 and the conductor pattern 502 of the mounting substrate 5 can be electrically connected through the first cover substrate 2 without using a bonding wire, and Since it is not necessary to provide a resin for protecting the bonding wire, it is possible to improve electrical connection reliability while suppressing unnecessary stress from being applied to the mirror forming substrate 1.

  Further, in the MEMS device of the present embodiment, the conductive portion 202 of the first cover substrate 2 is within the thickness dimension of the first cover substrate 2 on the opposite side of the first cover substrate 2 from the mirror forming substrate 1 side. Since it extends to the side surface, the connection reliability between the conductive portion 202 and the conductor pattern 502 can be improved.

  Further, in the MEMS device of the present embodiment, in the MEMS chip 4, a space surrounded by the outer frame portion 10, the first cover substrate 2, and the second cover substrate 3 constituting the peripheral portion of the mirror forming substrate 1 is formed. Since it is an airtight space, it is possible to improve device characteristics (in this embodiment, the mechanical deflection angle of the movable portion 20).

  Further, in the MEMS device of the present embodiment, the airtight space of the MEMS chip 4 is a vacuum atmosphere, and the getter 9 is disposed in a portion of the second cover substrate 3 facing the airtight space. The degree of vacuum can be increased and the change in the degree of vacuum in the hermetic space can be suppressed, and the change in device characteristics (in this embodiment, the mechanical deflection angle of the movable portion 20) due to the change in degree of vacuum can be reduced. Can be prevented. Depending on the structure of the MEMS chip 4, the getter 9 may be disposed at a portion of the first cover substrate 2 that faces the airtight space, or the first cover substrate 2 and the second cover substrate 3 may be disposed. You may make it arrange | position the getter 9 in both.

(Embodiment 2)
In the present embodiment, as an example of a MEMS device, an optical scanner is illustrated as in the first embodiment.

  Hereinafter, the optical scanner of this embodiment will be described with reference to FIGS.

  The basic configuration of the MEMS device of the present embodiment is substantially the same as that of the first embodiment, and the structures of the movable portion 20 and the first cover substrate 2 are different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

  In the present embodiment, the movable portion 20 is a frame-like shape that is swingably supported by the outer frame portion 10 via a pair of torsion spring portions 30 and 30 (hereinafter referred to as first torsion spring portions 30 and 30). A movable frame portion 23 (here, a rectangular frame shape), a mirror portion 24 having a rectangular shape in plan view provided on the inner side of the movable frame portion 23 and provided with a mirror surface 21, and a mirror portion inside the movable frame portion 23 And a pair of torsion spring portions 25 and 25 (hereinafter referred to as second torsion spring portions 25 and 25) that are arranged so as to sandwich 24 and connect the movable frame portion 23 and the mirror portion 24 and can be torsionally deformed. is doing.

  The second torsion spring portions 25, 25 are arranged in parallel in a direction (x-axis direction) orthogonal to the parallel arrangement direction (y-axis direction) of the first torsion spring portions 30, 30. In short, the movable portion 20 has a pair of second torsion spring portions 25, 25 arranged in parallel in the x-axis direction, and the mirror portion 24 is a pair of second torsion spring portions 25 with respect to the movable frame portion 23. , 25 (displaceable around the axis in the x-axis direction). That is, the pair of second torsion spring portions 25, 25 connect the movable frame portion 23 and the mirror portion 24 so that the mirror portion 24 can swing with respect to the movable frame portion 23. In other words, the mirror part 24 disposed inside the movable frame part 23 is movable frame part via two second torsion spring parts 25, 25 extended continuously and integrally from the mirror part 24 in two opposite directions. 23 is swingably supported. Here, the pair of second torsion spring portions 25 and 25 are formed such that a straight line connecting the center lines along the x-axis direction passes through the center of gravity of the mirror portion 24 in plan view. Each of the second torsion springs 25 and 25 has a thickness dimension (z-axis direction dimension) set to 30 μm and a width dimension (y-axis direction dimension) set to 30 μm. There is no particular limitation. Moreover, the planar view shape of the mirror part 24 and the mirror surface 21 is not restricted to a rectangular shape, For example, a circular shape may be sufficient. Further, the inner peripheral shape of the movable frame portion 23 is not limited to a rectangular shape, and may be a circular shape, for example.

  As can be seen from the above description, the mirror portion 24 is configured to rotate around the axis of the pair of first torsion spring portions 30 and 30 and rotate around the axis of the pair of second torsion spring portions 25 and 25. Is possible. In short, the mirror surface 21 of the mirror unit 24 is configured to be two-dimensionally rotatable. Here, the movable portion 20 includes a frame-like support body 29 that is integrally provided on the opposite side of the movable frame portion 23 to the first cover substrate 2 side, and supports the movable frame portion 23. 29 is rotatable integrally with the movable frame portion 23.

  Therefore, in the second cover substrate 3, the depth dimension of the concave portion 301 in the glass substrate 300 is set larger than that in the first embodiment.

  Further, in the present embodiment, three pads 13 are arranged in parallel at substantially equal intervals so as to be aligned on the outer frame portion 10 in plan view, and each pad 13 is arranged on the first cover substrate 2. Three electrically conductive portions 202 that are electrically connected pass through, and each electrically conductive portion 202 includes an extending portion 203.

  Moreover, the mirror formation board | substrate 1 in the MEMS device of this embodiment is the direction which connects a pair of 1st torsion spring parts 30 and 30 in the movable part 20 similarly to Embodiment 1 (a pair of 1st torsion spring parts 30, Comb-shaped movable electrodes 22 (hereinafter referred to as first movable electrodes 22) formed on both sides in a direction (that is, the x-axis direction) orthogonal to the direction of 30 parallel arrangements) and formed on the outer frame portion 10. And two comb-shaped fixed electrodes 12 (hereinafter referred to as first fixed electrodes 12) each having a plurality of fixed comb teeth 12b facing the plurality of movable comb teeth 22b of the first movable electrode 22. ing. Furthermore, the mirror forming substrate 1 is perpendicular to the direction in which the pair of second torsion spring portions 25, 25 are connected in the mirror portion 24 (the direction in which the pair of second torsion spring portions 25, 25 are arranged in parallel) (that is, Comb-shaped second movable electrodes 27 formed on both sides in the y-axis direction) and a plurality of fixed combs formed on the movable frame portion 23 and facing the plurality of movable comb teeth 27b of the second movable electrode 27 And two comb-shaped second fixed electrodes 26 having tooth pieces 26b. Thus, the mirror forming substrate 1 includes a set of the first movable electrode 22 and the first fixed electrode 12, a set of the second movable electrode 27 and the second fixed electrode 26, each of which is a movable part by electrostatic force. An electrostatic drive type driving means for driving 20 is configured.

  The above-mentioned second fixed electrode 26 has a comb shape in plan view, the comb bone portion 26a is constituted by a part of the movable frame portion 23, and the surface of the comb bone portion 26a facing the mirror portion 24 ( A large number of fixed comb teeth 26b are arranged in a line along the direction in which the pair of second torsion springs 25, 25 are arranged on the inner surface of the movable frame 23 along the x-axis direction. On the other hand, the second movable electrode 27 is configured by a part of the mirror portion 24, and the side surface of the second fixed electrode 26 on the side of the comb portion 26 a (the side surface along the x-axis direction in the mirror portion 24). A large number of movable comb teeth 27b facing the fixed comb teeth 26b are arranged in the parallel direction. Here, in the comb-shaped second fixed electrode 26 and the comb-shaped second movable electrode 27, the comb bone portions 26a and 27a are opposed to each other, and each fixed comb tooth piece 26b of the second fixed electrode 26 is The second movable electrode 27 is inserted into the comb groove. Therefore, the second fixed electrode 26 and the second movable electrode 27 are such that the fixed comb tooth piece 26b and the movable comb tooth piece 27b are separated from each other in the x-axis direction. Thus, in the mirror forming substrate 1, a voltage is applied between the second fixed electrode 26 and the second movable electrode 27, so that a gap between the second fixed electrode 26 and the second movable electrode 27 is obtained. An electrostatic force acting in a direction attracting each other is generated. In addition, what is necessary is just to set the clearance gap between the fixed comb-tooth piece 26b in the x-axis direction and the movable comb-tooth piece 27b suitably in the range of about 2 micrometers-5 micrometers, for example.

  The mirror forming substrate 1 is formed with a plurality of (three in the illustrated example) slits 10 a in the portion formed by the first silicon layer 100 a in the outer frame portion 10, and at the movable frame portion 23 of the movable portion 20. A plurality of (four in the illustrated example) slits 20a are formed in a portion formed by one silicon layer 100a, so that among the three pads 13, the middle pad 13 (13b) in FIG. The right pad 13 (13a) is electrically connected to the first movable electrode 22 and the second fixed electrode 26 to have the same potential by being electrically connected to the fixed electrode 12. The pad 13 (13c) is electrically connected to each second movable electrode 27 of the mirror portion 24 and has the same potential.

  Here, the plurality of slits 10a of the outer frame portion 10 are formed with a depth reaching the insulating layer 100c. Also in the present embodiment, as in the first embodiment, each slit 10a is a trench, and the shape of each slit 10a in plan view is a shape that does not open to the outer surface side of the outer frame portion 10, so that the outer frame portion 10 has a slit. While adopting the structure in which 10a is formed, it is possible to prevent the bonding property between the outer frame portion 10 and the first cover substrate 2 from being lowered, and to prevent the outer frame portion 10, the first cover substrate 2 and the second cover from being deteriorated The airtightness of the space surrounded by the substrate 3 is ensured.

  In addition, each slit 20a of the movable frame portion 23 in the movable portion 20 is a trench, and the above-described support 29 is configured by a part of the insulating layer 100c of the SOI substrate 100 and a part of the second silicon layer 100b. The depth reaches the insulating layer 100c. In short, in this embodiment, since the movable frame portion 23 is supported by the support body 29 while adopting the configuration in which the plurality of slits 20a are formed in the movable frame portion 23, the movable frame portion 23 and the support body 29 are provided with each other. The pair of first torsion spring portions 30 and 30 can be integrally rotated around the axis. Here, the support body 29 is formed in a frame shape (rectangular frame shape) that covers a portion of the movable frame portion 23 excluding each fixed comb tooth piece 26b and each movable comb tooth piece 22b (see FIG. 8). In addition, the plurality of trenches 20a of the movable frame portion 23 has the center of gravity of the movable portion 20 including the support 29 centered along the y-axis direction of the pair of first torsion spring portions 30 and 30 in plan view. The shape is designed so that it is positioned approximately in the middle of the connecting straight line. Accordingly, the movable portion 20 smoothly swings around the axis of the pair of first torsion spring portions 30 and 30, and the reflected light is properly scanned. In the present embodiment, the thickness of the portion constituted by the second silicon layer 100b in the support 29 is set to the same thickness as the portion constituted by the second silicon layer 100b in the outer frame portion 10. Although it is not limited to the same, it may be thicker or thinner.

  In the MEMS device of the present embodiment, for example, the first fixed electrode 12 and the second movable electrode 12 are set using the potential of the pad 13a to which the first movable electrode 22 and the second fixed electrode 26 are electrically connected as a reference potential. By periodically changing the potential of each of the electrodes 27, the movable portion 20 can be rotated about the axis of the pair of first torsion spring portions 30, 30, and the mirror portion 24 can be turned to the pair of second torsion springs. The torsion springs 25 and 25 can be rotated around the axis. In short, by applying a pulse voltage for driving the movable portion 20 between the first fixed electrode 12 and the first movable electrode 22 facing each other through the pair of pads 13b and 13a, the first fixed electrode 12 is provided. An electrostatic force is generated between the first movable electrodes 22, the movable portion 20 rotates about the axis in the y-axis direction, and the second fixed electrode 26 and the second electrode 26 facing each other through the pair of pads 13 a and 13 c. By applying a pulse voltage for driving the mirror portion 24 between the two movable electrodes 27, an electrostatic force is generated between the second fixed electrode 26 and the second movable electrode 27, and the mirror portion 24 It rotates around the axis in the axial direction. Therefore, in the MEMS device of this embodiment, an electrostatic force is periodically generated by applying a pulse voltage having a predetermined first driving frequency between the first fixed electrode 12 and the first movable electrode 22. Further, the entire movable part 20 can be swung, and the period can be increased by applying a pulse voltage having a predetermined second driving frequency between the second fixed electrode 26 and the second movable electrode 27. Thus, electrostatic force can be generated and the mirror part 24 of the movable part 20 can be swung. The mirror forming substrate 1 in the present embodiment is a surface of a portion where the reflective film 21a of the first silicon layer 100a is not formed on the space side surrounded by the outer frame portion 10 and the first cover substrate 2. In addition, a silicon oxide film 111a (see FIG. 10C) is formed.

  In the MEMS device of the present embodiment, the resonance frequency of the vibration system configured by the movable portion 20 and the pair of first torsion spring portions 30 and 30 is between the first fixed electrode 12 and the first movable electrode 22. By applying a pulse voltage having a frequency approximately doubled, the movable portion 20 is driven with a resonance phenomenon, and the mechanical deflection angle (inclination with respect to a horizontal plane parallel to the xy plane) is increased. Further, in the MEMS device of the present embodiment, the resonance of the vibration system configured by the mirror portion 24 and the pair of second torsion spring portions 25 and 25 between the second fixed electrode 26 and the second movable electrode 27. By applying a pulse voltage having a frequency that is approximately twice the frequency, the mirror unit 24 is driven with a resonance phenomenon, and a mechanical deflection angle (a surface parallel to the surface of the movable frame unit 23 on the first cover substrate 2 side). (Slope with respect to) increases.

  Hereinafter, a method for manufacturing the MEMS chip 4 in the present embodiment will be described with reference to FIGS. 9 and 10. FIGS. 9A to 9C and FIGS. 10A to 10C are illustrated in FIG. The schematic cross section of the part corresponding to -B cross section is shown.

  First, in the first silicon layer 100a of the SOI substrate 100 that is a semiconductor substrate, a region inside the region corresponding to the outer frame portion 10 is thinned by using a photolithography technique and an etching technique. Thereafter, an oxide film forming step for forming silicon oxide films 111a and 111b on the one surface side and the other surface side of the SOI substrate 100 by a thermal oxidation method or the like is performed, thereby obtaining the structure shown in FIG. .

  Thereafter, a portion of the silicon oxide film 111a on the one surface side of the SOI substrate 100 other than the region where the reflective film 21a is to be formed in the movable portion 20, a portion corresponding to the first torsion spring portions 30, 30, and the like remain. Further, a structure shown in FIG. 9B is obtained by performing a first silicon layer patterning step of patterning the first silicon layer 100a using a photolithography technique and an etching technique.

  Thereafter, a metal film forming step of forming a metal film (for example, an Al film) having a predetermined film thickness (for example, 500 nm) on the one surface side of the SOI substrate 100 by a sputtering method, a vapor deposition method, or the like is performed. Then, by performing a metal film patterning step of forming each pad 13 and the reflective film 21a by patterning the metal film using an etching technique, the structure shown in FIG. 9C is obtained. In this embodiment, since the material and film thickness of each pad 13 and the reflective film 21a are set to be the same, each pad 13 and the reflective film 21a are formed simultaneously. When the material and film thickness of the film 21a are different, the pad forming process for forming each pad 13 and the reflective film forming process for forming the reflective film 21a may be provided separately.

  After forming each of the pads 13 and the reflective film 21a, the movable frame portion 23, the mirror portion 24, and the pair of first torsion spring portions 30 in the first silicon layer 100a are formed on the one surface side of the SOI substrate 100. , 30, a pair of second torsion spring portions 25, 25, the outer frame portion 10, each first fixed electrode 12, each second movable electrode 22, each second fixed electrode 26, and each second movable electrode A first resist layer 107 is formed so as to cover a portion corresponding to 27. Then, by performing a first silicon layer patterning step (surface-side patterning step) in which the first silicon layer 100a is patterned by etching the first silicon layer 100a using the first resist layer 107 as a mask. The structure shown in FIG. In the first silicon layer patterning step, the first silicon layer 100a is etched to a depth that reaches the insulating layer 100c (first predetermined depth). Etching of the first silicon layer 100a in the first silicon layer patterning step may be performed by a dry etching apparatus capable of highly anisotropic etching such as an inductively coupled plasma (ICP) type etching apparatus. In the first silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

  After the first silicon layer patterning step, the first resist layer 107 on the one surface side of the SOI substrate 100 is removed. Thereafter, a second resist layer 108 is formed on the entire surface of the SOI substrate 100 on the one surface side, and then, on the other surface side of the SOI substrate 100, the outer frame portion 10 and the support body of the second silicon layer 100b. A third resist layer 109 patterned so as to expose portions other than those corresponding to 29 is formed. Thereafter, by performing a second silicon layer patterning step of patterning the second silicon layer 100b by etching the second silicon layer 100b using the third resist layer 109 as a mask, FIG. Get the structure shown. In this second silicon layer patterning step, etching is performed to a depth (second predetermined depth) reaching the insulating layer 100c. Etching of the second silicon layer 100b in the second silicon layer patterning step may be performed by a dry etching apparatus that has high anisotropy and enables vertical deepening, such as an inductively coupled plasma (ICP) etching apparatus. In the second silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

  After the second silicon layer patterning step, the mirror forming substrate 1 is formed by performing an insulating layer patterning step of etching unnecessary portions of the insulating layer 100c of the SOI substrate 100 from the other surface side of the SOI substrate 100. Subsequently, the second resist layer 108 and the third resist layer 109 are removed. Thereafter, the MEMS chip 4 having the structure shown in FIG. 10C is obtained by performing a bonding step of bonding the mirror forming substrate 1 to the first cover substrate 2 and the second cover substrate 3 by anodic bonding or the like. . Here, in the bonding step, from the viewpoint of protecting the mirror surface 21 of the mirror forming substrate 1, after performing a first bonding process for bonding the first cover substrate 2 and the mirror forming substrate 1, the mirror forming substrate 1. It is preferable to perform a second joining process for joining the first cover substrate 3 and the second cover substrate 3. Note that, after the first silicon layer patterning step, the SOI substrate 100 and the first cover substrate 2 are bonded together, and then the second silicon layer patterning step and the insulating layer patterning step are performed, whereby the mirror forming substrate 1 is formed. Then, the mirror forming substrate 1 and the second cover substrate 3 may be bonded.

By the way, in the manufacturing method of the MEMS chip 4 in the present embodiment, as in the first embodiment,
A wafer level package structure including a plurality of MEMS chips 4 is formed by performing all processes up to the end of the bonding process at the wafer level for each of the mirror forming substrate 1 and each of the cover substrates 2 and 3. A dividing step of dividing the package structure into individual MEMS chips 4 is performed. In short, in the manufacturing method of the MEMS chip 4 in the present embodiment, the first wafer on which a plurality of mirror forming substrates 1 are formed, the second wafer on which a plurality of first cover substrates 2 are formed, and the second cover substrate 3 are provided. After the wafer level package structure is formed by joining a plurality of formed third wafers, the wafer level package structure is divided into the outer size of the mirror forming substrate 1. 3 plane size can be matched with the external size of the mirror forming substrate 1.

  According to the MEMS device (optical scanner) of the present embodiment described above, each pad 13 of the mirror forming substrate 1 is joined and electrically connected to the first cover substrate 2 as in the first embodiment. A plurality of conductive parts 202 made of silicon are provided within the thickness dimension of the second cover substrate 2, and each conductive part 202 and each conductive pattern 502 associated with each conductive part 202 in the mounting substrate 5 are provided. The conductive portion 202 and the conductive pattern 502 are electrically connected via the solder portion 6 formed over the conductive portion 202 and the conductive pattern 502. Thus, in the MEMS device of the present embodiment, the pad 13 of the mirror forming substrate 1 and the conductor pattern 502 of the mounting substrate 5 can be electrically connected through the first cover substrate 2 without using a bonding wire, and Since it is not necessary to provide a resin for protecting the bonding wire, it is possible to improve electrical connection reliability while suppressing unnecessary stress from being applied to the mirror forming substrate 1.

  Also in the MEMS device of the present embodiment, the conductive portion 202 has the first cover substrate 2 within the thickness dimension of the first cover substrate 2 on the opposite side of the first cover substrate 2 from the mirror forming substrate 1 side. Therefore, the connection reliability between the conductive portion 202 and the conductor pattern 502 can be improved.

  Further, in the MEMS device of the present embodiment, the mirror forming substrate 1 includes the outer frame portion 10, the pair of first twisted portions 30, 30, the movable frame portion 23, and the pair of second twisted portions 25. , 25, the mirror section 24, the first fixed electrodes 12, the first movable electrodes 22, the second fixed electrodes 26, and the second movable electrodes 27, and the first movable electrodes 22. Since each pad 13 electrically connected to each first fixed electrode 12, each second movable electrode 27, and each second fixed electrode 26 is disposed on the outer frame portion 10, the mirror portion 24 can rotate around the axis of the pair of first torsion springs 30 and 30 and rotate around the axis of the pair of second torsion springs 25 and 25, and each pad 13. And the reliability of bonding between the conductive portions 202 can be improved.

  By the way, in each said embodiment, although illustrated about the optical scanner as an example of a MEMS device, a MEMS device is not restricted to an optical scanner, For example, the vibration which converts an acceleration sensor, a gyro sensor, a micro relay, vibration energy into electrical energy, for example. A power generation device of the type, a BAW (Bulk Acoustic Wave) resonance device including a resonator using a longitudinal vibration mode in the thickness direction of the piezoelectric layer, an infrared sensor, or the like may be used.

1 Mirror forming substrate (device body)
2 First cover substrate (front side protection substrate)
3 Second cover substrate (back side protection substrate)
4 MEMS chip 5 Mounting substrate 6 Solder part 9 Getter 10 Outer frame part 12 Fixed electrode (first fixed electrode)
13 Pad 22 Movable electrode (first movable electrode)
DESCRIPTION OF SYMBOLS 23 Movable frame part 24 Mirror part 25 2nd twisting part 26 2nd fixed electrode 27 2nd movable electrode 30 1st twisting part 100 SOI substrate (semiconductor substrate)
202 Conductive part 203 Extension part 501 Concave part 502 Conductor pattern

Claims (6)

  A device body formed using a semiconductor substrate and provided with a plurality of pads on one surface side, a MEMS chip having a surface-side protective substrate bonded to the one surface side of the device body, and a mounting on which the MEMS chip is mounted A plurality of conductive portions made of silicon bonded to and electrically connected to each of the pads of the device body within the thickness dimension of the surface-side protection substrate. And each conductive part and each conductive pattern associated with each conductive part in the mounting substrate are electrically connected via a solder part formed across the conductive part and the conductive pattern. A MEMS device connected to the device.   The conductive portion is extended to a side surface of the front surface side protective substrate within the thickness dimension of the front surface side protective substrate on a side opposite to the device main body side of the front surface side protective substrate. Item 2. The MEMS device according to Item 1.   The MEMS chip includes a back surface side protective substrate bonded to the other surface side of the device body, and a space surrounded by the peripheral portion of the device body, the front surface side protective substrate, and the back surface side protective substrate is defined as an airtight space. The MEMS device according to claim 1, wherein the MEMS device is provided.   4. The MEMS chip according to claim 3, wherein the airtight space is in a vacuum atmosphere, and a getter is disposed at a portion facing the airtight space on one of the front surface side protective substrate and the back surface side protective substrate. The described MEMS device.   The said mounting substrate has a recessed part recessed from the plane containing the said conductor pattern, The said MEMS chip is mounted in the inner bottom face of the said recessed part, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The MEMS device according to item.   The device body includes an outer frame portion to which a peripheral portion of the surface-side protective substrate is bonded on the one surface side, and a pair of first twisted portions disposed on the inner side of the outer frame portion. Via a movable frame portion supported by a portion, and a pair of second twisted spring portions positioned inside the movable frame portion and juxtaposed in a direction perpendicular to the juxtaposed direction of the first twisted spring portions. A mirror part supported by the movable frame part, a first fixed electrode provided on the movable frame part side in the outer frame part, and a first provided on the outer frame part side in the movable frame part A movable electrode; a second fixed electrode provided on the mirror part side in the movable frame part; and a second movable electrode provided on the movable frame part side in the mirror part. Each pad electrically connected to each of the first movable electrode, the first fixed electrode, the second movable electrode, and the second fixed electrode is disposed on the outer frame portion. The MEMS device according to any one of claims 1 to 5, wherein

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